抚仙湖夏季热分层时期浮游植物空间分布特征

Spatial distribution of phytoplankton community during summer stratification in Lake Fuxian

抚仙湖是云贵高原典型的深水贫营养湖泊。为了研究其浮游植物群落的空间分布特征和影响因子,于2014年7月在抚仙湖设置了3个采样点进行分层采样。结果表明:共检出浮游植物37种,隶属于6门18科27属;全湖浮游植物的平均生物量为0.41mg·L^(-1),其中绿藻门的比例超过70%;绿藻门中的转板藻(Mougeotia sp.)是夏季抚仙湖浮游植物中的绝对优势种,平均生物量为0.18 mg·L^(-1);在水平分布上,浮游植物生物量在北部湖区大于中部和南部;在垂直分布上,浮游植物主要分布在湖体的表层和温跃层,最大值出现在水面以下10 m,深水层的生物量显著降低。线性相关性分析表明,表层和温跃层浮游植物生物量主要受水深变化引起的一系列环境变量如水温、光照等变化的影响,而影响深水层浮游植物生物量的主要因子是溶解氧和pH。冗余分析显示,环境变量较好地解释了浮游植物群落组成的空间变化,水温、电导率和pH是最关键的几个影响因子,氮、磷营养盐的作用并不显著。本研究对探究亚热带高原深水湖泊浮游植物群落的分布特征具有积极意义。

Lake Fuxian is a typical deep oligotrophic lake located in YunnanGuizhou Plateau. In order to explore the spatial distribution characteristics of the phytoplankton community and its influencing factors, stratified sampling, including three sites, was conducted in July 2014. A total of 37 species, belonging to 27 genera, 18 families and 6 phyla, were identified in our survey. The average biomass of phytoplankton across the whole lake was 0.41 mg·L^-1, of which Chlorophyta exceeded 70%. Mougeotia sp., which belongs to Chlorophyta, was the absolutely dominant species with a biomass of 0.18 mg·L^-1. In horizontal distribution, biomass of phytoplankton was higher in the north than those in the middle and south. In water column, phytoplankton was mainly distributed in epilimnion and thermocline layers with a maximum occurring at a depth of 10 m, and the biomass decreased remarkably in hypolimnion layer. Correlation analysis suggested that biomass of phytoplankton in epilimnion and thermocline layers was mainly influenced by water depth （accompanied with water temperature and light）, while in hypolimnion layer the key affecting factors were DO and pH. Redundancy analysis demonstrated that environmental variables well explained the variations in phytoplankton communities. Water temperature, electric conductivity and pH played key roles in structuring phytoplankton communities, while the role of N and P nutrients was not significant.